Assessment of the recent land use change dynamics related to sugarcane expansion and the associated effects on water resources availability

In this work, the Soil and Water Assessment Tool (SWAT) model was used to assess the impacts of the recent sugarcane expansion dynamics on the local water availability of two Brazilian basins (Fazenda Monte Alegre - FMA; Monte Mor - MM), which have experienced different land use change trends. To mitigate the issues concerning SWAT crop growth and water balance, it was performed for both basins a comprehensive model calibration and validation processes. Based on the results for water yields in FMA basin, it was possible to concluded that the sugarcane expansion over annual crops tends to increase stream flow during dry periods and decrease peak flows. In MM basin, the water yields suggest that urban areas expansion increases the stream flow in wet months, which can possibly harm flood vulnerability. In addition to these indications, the calibrated and validated SWAT model produced in this work can also be employed for the assessment of future scenarios with respect to not only land use changes, but also climate changes19713281341CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPNão temNão temThis study was developed in the context of the projects “Integrated Sustainability Assessment of Bioethanol Production from Sugarcane in Brazil” (2011/51710-2), funded by the São Paulo Research Foundation (FAPESP), and “Sugarcane Renewable Electricity” (BRA/10/G31), funded by the Global Environment Facility (GEF). JEAS thankfully acknowledges the support from CNP

Performance of a reciprocal shaker in mechanical dispersion of soil samples for particle-size analysis

A dispersão da amostra de solo é uma etapa fundamental da análise granulométrica, sendo realizada mediante o uso de dispersantes químicos e agitação mecânica. O objetivo deste trabalho foi avaliar a eficiência de mesa agitadora reciprocante de baixa rotação na dispersão mecânica de amostras de solos de diferentes classes texturais. Foram realizadas análises granulométricas em 61 amostras com quatro repetições, empregando o método da pipeta para determinação da fração argila e tamisagem para determinação das frações areia grossa, areia fina e areia total, sendo o silte determinado por diferença. Na avaliação de desempenho, os resultados obtidos com uso da mesa agitadora reciprocante (MAR) foram comparados com dados disponíveis para as mesmas amostras oriundos de relatórios do Ensaio de Proficiência IAC para Laboratórios de Análises de Solos - Prolab/IAC. Análises de acurácia foram realizadas com base nos valores dos intervalos de confiança definidos para cada fração granulométrica componente de cada amostra ensaiada. Indicadores gráficos também foram utilizados na comparação de dados, por meio de dispersão e ajuste linear. A estatística descritiva indicou preponderância de baixa variabilidade em mais de 90 % dos resultados obtidos para as amostras de texturas arenosa, média e argilosa e em 68 % dos obtidos para as amostras de textura muito argilosa, indicando boa repetibilidade dos resultados obtidos com a MAR. Média variabilidade foi mais frequentemente associada à fração silte, seguida da fração areia fina. Os resultados das análises de sensibilidade indicam acurácia de 100 % nas três frações granulométricas - areia total, silte e argila - para todas as amostras analisadas pertencentes às classes texturais muito argilosa, argilosa e média. Para as nove amostras de textura arenosa, a acurácia média foi de 85,2 %, e os maiores desvios ocorreram em relação à fração silte. Nas aproximações lineares, coeficientes de correlação igual (silte) ou superiores (areia total e argila) a 0,93, bem como diferenças menores do que 0,16 entre os coeficientes angulares das retas e o valor unitário, indicam alta correlação entre os resultados de referência (Prolab/IAC) e os obtidos nos ensaios com a MAR. Conclui-se pelo desempenho satisfatório da mesa agitadora reciprocante de baixa rotação para dispersão mecânica de amostras de solo de diferentes classes texturais para fins de análise granulométrica, permitindo recomendar o uso alternativo do equipamento quando se emprega agitação lenta. As vantagens do uso do equipamento nacional incluem o baixo custo, a possibilidade de análise simultânea de grande número de amostras e o uso de frascos comuns, de vidro ou de plástico, baratos e de fácil reposição.The dispersion of the samples in soil particle-size analysis is a fundamental step, which is commonly achieved with a combination of chemical agents and mechanical agitation. The purpose of this study was to evaluate the efficiency of a low-speed reciprocal shaker for the mechanical dispersion of soil samples of different textural classes. The particle size of 61 soil samples was analyzed in four replications, using the pipette method to determine the clay fraction and sieving to determine coarse, fine and total sand fractions. The silt content was obtained by difference. To evaluate the performance, the results of the reciprocal shaker (RSh) were compared with data of the same soil samples available in reports of the Proficiency testing for Soil Analysis Laboratories of the Agronomic Institute of Campinas (Prolab/IAC). The accuracy was analyzed based on the maximum and minimum values defining the confidence intervals for the particle-size fractions of each soil sample. Graphical indicators were also used for data comparison, based on dispersion and linear adjustment. The descriptive statistics indicated predominantly low variability in more than 90 % of the results for sand, medium-textured and clay samples, and for 68 % of the results for heavy clay samples, indicating satisfactory repeatability of measurements with the RSh. Medium variability was frequently associated with silt, followed by the fine sand fraction. The sensitivity analyses indicated an accuracy of 100 % for the three main separates (total sand, silt and clay), in all 52 samples of the textural classes heavy clay, clay and medium. For the nine sand soil samples, the average accuracy was 85.2 %; highest deviations were observed for the silt fraction. In relation to the linear adjustments, the correlation coefficients of 0.93 (silt) or > 0.93 (total sand and clay), as well as the differences between the angular coefficients and the unit < 0.16, indicated a high correlation between the reference data (Prolab/IAC) and results obtained with the RSh. In conclusion, the mechanical dispersion by the reciprocal shaker of soil samples of different textural classes was satisfactory. The results allowed recommending the use of the equipment at low agitation for particle size- analysis. The advantages of this Brazilian apparatus are its low cost, the possibility to simultaneously analyze a great number of samples using ordinary, easily replaceable glass or plastic bottles

Sugarcane drought detection through spectral indices derived modeling by remote-sensing techniques

Several indices based on satellite images have been explored to monitor agricultural drought. Despite the existence of some drought indices, no drought monitoring system for sugarcane exists. In this sense, drought detection could be useful tool to quantify losses and help with action plans. This study investigates the Landsat image potential for sugarcane drought detection by assessing the relationship between vegetation and agricultural drought indices (normalized difference vegetation index (NDVI), vegetation condition index (VCI), normalized difference water index (NDWI), global vegetation moisture index (GVMI), and normalized difference infrared index (NDII)). Two new indices combining near-infrared (NIR) and short-wave infrared (SWIR) bands are proposed for sugarcane drought detection. All indices were individually and collectively compared with soil water deficit and water surplus, simulated by the climatological soil-water balance (CSWB) model. A significant correlation between spectral indices and water balance results, specifically for NDVI and VCI indices (similar to 30%), was observed. The drought detection system identification was developed by cluster analysis classifying the pixels into three distinct groups (drought, intermediate drought, and non-drought) to later be used in the discriminant analysis. This methodology showed to have an accuracy rate of 65%. However, the discriminant analysis approach was better suited for sugarcane drought monitoring when compared with individual spectral indices541679FAPESP – Fundação de Amparo à Pesquisa Do Estado De São Paulo2014/17090-

Integrating carbon footprint to spatialized modeling: The mitigation potential of sugarcane ethanol production in the Brazilian Center-South

International audienceBiomass cultivation has a large influence over the resulting bio-based products and is largely influenced by local conditions. Therefore, accounting for spatialization into sustainability assessments under the life-cycle perspective is key. The study aims to integrate satellite image classification for sugarcane areas in the Center -South of Brazil with georeferenced modeling for sugarcane yield and ethanol production. 290 ethanol mills were simulated, and the resulting inventories were used to trace ethanol's carbon footprint spatial profile and mitigation potential for gasoline substitution. Ethanol's carbon intensity varied from 14.38 to 34.0 gCO2e.MJ- 1, with an average of 18.41 gCO2e.MJ-1. By translating these indicators into Decarbonization Credits (CBIOS), under the RenovaBio program, a GHG mitigation potential of 45.07 MtCO2e could be annually attributed to the current Brazilian ethanol sector, corresponding to an additional revenue of US$ 0.88 billion. The proposed georeferenced framework showed significant spatial variations that should be accounted in future sustainability assessments

Straw removal effects on soil water dynamics, soil temperature, and sugarcane yield in South-Central Brazil

The use of sugarcane straw as bioenergy feedstock has been encouraged in recent years due to its potential to mitigate greenhouse gases emissions. Nevertheless, the indiscriminate straw removal causes soil damages, impairing crop development and productivity. Experiments in three sugarcane growing locations (Quata-SP, Chapadao do Ceu-GO, and Quirinopolis-GO) were conducted over 2 years to evaluate soil water dynamics, soil temperature, and sugarcane yield under diverse edaphoclimatic conditions. Straw removal of 0%, 50%, and 100% was arranged in a randomized block design with four replications. Dielectric water potential sensors were used to record soil water potential (psi, kPa) and soil temperature (degrees C) every 6 h at a 0.15-m depth. Sugarcane yields were measured annually using an instrumented truck equipped with load cells. In general, the complete and partial straw removals were detrimental to water storage and therefore to plant available water causing an increase in soil temperature during sprouting and tillering phases, which are extremely important periods for a good crop establishment and, consequently, for yield increase. For the experimental sites presenting high fertility, greater water holding capacity, high sugarcane yield potential, and considering an extended water deficit in early stages of crop development, the complete straw removal resulted in yield losses of up to 16 and 40 Mg ha(-1), respectively. For the experimental site presenting low sugarcane yield potential, even with low water deficit at the beginning of crop seasons, straw removal had no significant influence on sugarcane yield in the short term, since straw did not produce enough improvements to soil in order to enable benefits for water retention124749763CNPQ - Conselho Nacional de Desenvolvimento Científico e TecnológicoFAPESP – Fundação de Amparo à Pesquisa Do Estado De São Paulo406922/2013-62016/09133-1The authors would like to thank the technical team of CTBE as well as the teams of the mills Quatá (Zilor Group), Cerradinho Bio, and Boa Vista (São Martinho group) for their help in conducting the experiments. F.V. Scarpare participated in this research in the context of FAPESP (2016/09133-1). This study was supported by the Sugarcane Renewable Electricity project - SUCRE/UNDP (grant number BRA/10/G31) and by the National Council for Scientific and Technological Development – CNPq (grant number 406922/2013-6

Modeling sugarcane development and growth within ECOSMOS biophysical model

International audienceSugarcane plays an important role in electricity and sugar production and is a viable biofuel. Developing and optimizing a mechanism that can predict crop growth and yield at different spatiotemporal scales can promote the understanding of the effects of cultivation on the ecosystem, while providing options for optimizing management measures and improving the operational procedures of sugarcane growers. The main objective of this study is to integrate the sugarcane module into the ECOSystem MOdel Simulator (ECOSMOS) model and calibrate a parameter set for sugarcane genotypes groups (using different datasets); the model supports datasets that vary in complexity (from flux tower experiments to operational plots), while accounting for high genotype-byenvironment-by-management (GxExM) variability. First, we calibrated the ECOSMOS biophysical and physiological parameters for the sugarcane module using two micrometeorological experimental sites, based on eddycovariance and biomass measurements. Second, sugarcane genotypes located in different regions of contrasting climate conditions were split into two groups based on their period of harvest, i.e., early or mid-to-late harvest season, and two parameter sets were proposed. The sugarcane module was used to estimate the yield of numerous plots, using two different parameter sets, namely, the general and regionally-specific parameter sets. The model could successfully simulate the biophysical and physiological processes of the biomass of stalks and leaves, energy and carbon fluxes, and soil-water dynamics; for Experimental Site 2, the Nash-Sutcliffe efficiency (NSE) was 0.14-0.86 and the relative root mean square error (RRMSE) was 13-112. However, the generic parameter set did not perform well in all production environments, and the difference between the observed and simulated yields ranged from 0.9 to 14.5 (Mg ha-1). Hence, a novel calibration approach adopted in this study improved the module's accuracy, while improving the performances for all five production environments, with the difference between the observed and simulate yields being 0.3-2.2 (Mg ha-1). Although the two parameter sets can be used as a reference for sugarcane plantations in Brazil, we recommend recalibrating the model (for ensuring higher accuracy) before operational applications. Notably, the ECOSMOS-sugarcane model is emerging as a complex ecosystem model that can support the quantifications and evaluations of the effects of sugarcane plantations on the carbon and water balances in different environmental conditions, particularly in tropical regions